I would say it is quite strange. This reminds me of issues I have seen come from plug-and-play drivers. When you go to www.hp.com/support and select the Drivers and Downloads link, type in 1536dnf and it will take you to a page to select which system type your Windows 7 is (32-bit or 64-bit). You will see 5 different drivers to try. I would start with the Full Feature Software and Drivers but usually that is the one everyone uses. Next try the Basic Print and Scan Drivers followed by PCL6 and so on. I know this doesn't sound like a very direct response but it is so hard to determine which one you are currently using. The links I have provided here are for Windows 7 64-bit US drivers.
--HP Product Detection-- This tool will help you verify which one hopefully. It is a web-based application depending on the web-browser you use so let me know if this doesn't help you. Or, even better, let me know which one does. :)
Let me know if you have any questions. I'm happy to help!